JP6446497B2 - Wire grid polarizer, projection display apparatus, and method of manufacturing wire grid polarizer - Google Patents

Description

  The present invention relates to a wire grid polarizer, a projection display apparatus, and a method for manufacturing a wire grid polarizer.

  In recent years, opportunities for using reflective polarizers in liquid crystal display devices have increased. The reflective polarizer reflects light of a specific linear polarization component and transmits light of a component orthogonal to the specific linear polarization component. Examples of the reflective polarizer include a polarizer made of a laminate of birefringent resin and a wire grid polarizer in which a plurality of conductors (metal thin wires) extend in parallel on a transparent substrate. Further, there is a polarizer made of cholesteric phase liquid crystal that reflects or transmits light of a specific circularly polarized light component instead of reflecting or transmitting light of a linearly polarized light component. Among these, light having a desired linearly polarized light component can be obtained with high polarization transmittance, and light having a linearly polarized light component orthogonal to the desired linearly polarized light component can be made to have a low polarization transmittance (high polarization reflectance). As a reflective polarizer, a wire grid polarizer has attracted attention. Note that the ratio of the light transmittance of two linearly polarized light components orthogonal to each other is referred to as the extinction ratio of the transmitted light.

  A wire grid type polarizer is generally a linearly polarized light having an electric field vector perpendicular to the extending direction of the metal fine wire in the incident light when the pitch of the metal fine wire is sufficiently smaller than the wavelength of the incident light. The light of the component is transmitted, and the light of the linearly polarized component having the electric field vector in the extending direction of the thin metal wire is reflected.

  As a method of manufacturing a wire grid polarizer, a thin film of a conductor is formed on the surface of a substrate, a polymer layer is formed on the thin film, and then a gold having a pattern formed by an interference exposure method or an electron beam drawing method is used. There is known a method (Patent Document 1) in which a pattern is formed on a polymer layer using a mold, and a thin metal film is formed by a dry etching method or the like using the pattern of the polymer layer. In addition, a method (Patent Document 2) is also known in which a conductor is vapor-deposited on the side surface of a convex portion of a base material by using an oblique vapor deposition method on a concave-convex base material. The former requires an expensive manufacturing apparatus necessary for interference exposure, electron beam drawing, dry etching, and the like, and has a problem of low productivity. On the other hand, since the latter manufacturing method can simplify a process, it can be made highly productive, and since a conductor is vapor-deposited on the side surface of a base material convex part, a conductor and The contact area of the substrate convex portion can be increased, and the loss of the conductor due to external force or the like can be reduced. Such a wire grid polarizer is hereinafter referred to as a wire grid polarizer.

  Since the wire grid polarizer is a reflective polarizer capable of high polarization reflectivity, it is possible to increase the brightness by recycling the light, and the generation of heat caused by the absorption of light is small. Suitable for

JP 2006-084776 A JP 2001-330728 A

  In recent years, with the advancement of broadcasting technology and image technology in liquid crystal display devices, higher image quality has been demanded. For this reason, the wire grid polarizing plate is also required to contribute to higher image quality.

  This invention is made | formed in view of this point, and provides the manufacturing method of the wire grid polarizing plate which can provide a higher-quality liquid crystal display device, a projection type video display apparatus, and a wire grid polarizing plate. One of the purposes.

The wire grid polarizing plate of the present invention includes a base material having a concavo-convex structure extending in a specific direction on the surface, and a conductor provided so as to be unevenly distributed on one side surface of the convex portion of the concavo-convex structure. a grid polarizer, the extending direction perpendicular to the cross section of the conductor or uneven structure (hereinafter, also referred to as cross-sectional view.) in the pitch P1 is an interval between adjacent two of the protrusions is at 120nm or less And the convex part height H which is the difference in height from the highest part of the convex part to the lowest part of the concave part is 0.8 to 1.3 times the pitch P1, and the extending direction of the concavo-convex structure in vertical cross section for, when the highest portion of the height difference of at least part of the location of the 9 / 10H first height position of the convex height H of the concave portion of the convex portion And between the first height position and the highest portion of the convex portion. Kicking Der horizontal thickness 20nm or more of the conductors is, the conductor extends to the highest portion from the outline lowest portion of the concave-convex structure, and at least a portion of the conductor, the said uneven structure It is provided above the highest part of the convex part, and the conductor has a thickness in the horizontal direction at a position of 1 / 10H of the convex part height H and a position at 9 / 10H of the convex part height H. The horizontal thickness at the highest portion of the conductor is smaller than the horizontal thickness at the highest portion of the convex portion .

  The projection-type image display apparatus of the present invention is a projection-type image display apparatus having the above-described wire grid polarizing plate, a light source, and a reflective liquid crystal display element, wherein light emitted from the light source is the wire grid polarization. Light is transmitted through or reflected by a plate to enter the reflective liquid crystal display element, and light modulated by the reflective liquid crystal display element is reflected or transmitted by the wire grid polarizing plate to project an image. .

The method for producing a wire grid polarizing plate of the present invention includes a step of forming a concavo-convex structure extending in a specific direction on a substrate surface, and a step of forming a conductor so as to be unevenly distributed on one side surface of the convex portion of the concavo-convex structure. When a method of manufacturing a wire grid polarizer having the step of forming the uneven structure is in the cross-sectional view in the vertical direction with respect to the extending direction of the uneven structure is the distance between adjacent two of said protrusions The pitch P1 is formed to be 120 nm or less, and the convex height H, which is the difference in height from the highest part of the convex part to the lowest part of the concave part, is 0.8 times to 1.3 times the pitch P1. and, the step of forming the conductor, said in the cross-sectional view in the vertical direction with respect to the extending direction of the convex-concave structure, the convex portion height is the height difference from the highest part to the lowest part of the concave portion of the convex portion 9 / 10H of height H is the first height position And when the horizontal thickness of the conductor between the first height position to the highest portion of the convex portion forming the conductor so that the above 20 nm, outline of the convex-concave structure The conductor is formed so as to extend from the lowest part to the highest part, and at least a part of the conductor is provided above the highest part of the convex part of the concavo-convex structure. The horizontal thickness at the position of 1 / 10H is larger than the horizontal thickness at the position of 9 / 10H of the height H of the convex portion, and the horizontal thickness at the highest portion of the conductor is the height of the convex portion. The conductor is formed so as to be thinner than the horizontal thickness at the highest portion .

  According to the present invention, it is possible to provide a liquid crystal display device with higher image quality.

It is a cross-sectional schematic diagram which shows an example of the wire grid polarizing plate which concerns on this Embodiment. It is a conceptual diagram which shows an example of the projection type video display apparatus concerning this Embodiment. It is a SEM photograph in the cross sectional view of the wire grid polarizing plate which concerns on the Example of this invention. It is a graph which shows the relationship between the parallel transmittance | permeability and orthogonal transmittance | permeability of the wire grid polarizing plate which concerns on the Example of this invention.

  Embodiments of the present invention will be described below.

<Relationship between optical symmetry of wire grid polarizer and image quality>
As a result of intensive studies to solve the above problems, the present inventors have found that the wire grid polarizing plate is optically symmetric due to the asymmetry of the structure composed of the conductor and the substrate convex portion in a sectional view. Since this shows a strong asymmetry and this changes the image state depending on the viewing angle, it has been found that there is a possibility of adversely affecting the image quality improvement of the liquid crystal display device using the wire grid polarizing plate. It came to be completed. That is, the present invention is as follows.

  The wire grid polarizing plate of the present invention includes a base material having a concavo-convex structure extending in a specific direction on the surface, and a conductor provided so as to be unevenly distributed on one side surface of the convex portion of the concavo-convex structure. In the grid polarizing plate, when the vertical direction of the wire grid polarizing plate is 0 degree, the difference in parallel transmittance (Tp) at the incident angles of −45 degrees and +45 degrees of the light having a wavelength of 555 nm is 4% or less. It is characterized by. If there is a difference in parallel transmittance exceeding 4%, it is not suitable because the viewer can recognize the image state, specifically the change in brightness, depending on the viewing angle.

  With such a configuration, the wire grid polarizer of the present invention can be suitably used for a liquid crystal display device that is viewed from various directions.

  Furthermore, when the specific structure of the wire grid polarizer of the present invention having the above-described characteristics is specified, for example, a substrate having a concavo-convex structure extending in a specific direction on the surface, and a convex portion of the concavo-convex structure On the other hand, a wire grid polarizing plate having a conductor provided so as to be unevenly distributed on the side surface, and a pitch that is an interval between two adjacent convex portions in a cross-sectional view perpendicular to the extending direction of the concavo-convex structure P1 is 120 nm or less, and the convex height H, which is the difference in height from the highest portion of the convex portion to the lowest portion of the concave portion, is 0.8 to 1.3 times the pitch P1.

  Examples of the video display device to which the wire grid polarizing plate of the present invention can be applied include a liquid crystal display device, a transmissive liquid crystal projector that is a projection video display device, a reflective liquid crystal projector, and the like.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Wire grid polarizer>
FIG. 1 is a schematic cross-sectional view of a wire grid polarizer according to an embodiment of the present invention. In addition, in FIG. 1, the schematic diagram in the perpendicular | vertical cross section with respect to the extending direction (the paper surface depth direction of FIG. 1 where a convex part and a recessed part each extend) of the uneven structure of the base material 11 of the wire grid polarizing plate 10 is shown. .

  As shown in FIG. 1, the wire grid polarizing plate 10 according to the present embodiment includes a base material 11 having a concavo-convex structure extending in a specific direction on the surface, and side surfaces 11b of the convex portions 11a on the surface of the base material 11. And a conductor 12 provided so as to be unevenly distributed on one side. The concavo-convex structure of the base material 11 is configured by repeating a plurality of convex portions 11a and a plurality of concave portions 11d.

  When the pitch of the conductor 12 is sufficiently smaller than the wavelength of incident light, the wire grid polarizer 10 has a linearly polarized light component having an electric field vector orthogonal to the extending direction of the conductor 12 in the incident light. Is transmitted, and the light of the linearly polarized light component having the electric field vector in the extending direction of the conductor 12 is reflected. The light transmittance of the linearly polarized light component having an electric field vector orthogonal to the extending direction of the conductor 12 is referred to as parallel transmittance, and the light of the linearly polarized light component having an electric field vector in the extending direction of the conductor 12 is transmitted. The rate is called orthogonal transmittance. In order to increase the extinction ratio of transmitted light expressed as the ratio of the parallel transmittance to the orthogonal transmittance, it is important to increase the parallel transmittance and lower the orthogonal transmittance.

  Next, the configuration of the concavo-convex structure of the wire grid polarizer 10 according to the present embodiment will be described in detail. In the following description, in the cross-sectional view of the surface of the base material 11, the interval between two adjacent convex portions 11a is defined as a pitch P1, and one of the side surfaces 11b of the convex portion 11a (hereinafter referred to as “one side surface”). The pitch between the conductors 12 that are unevenly distributed is defined as a pitch P2. The difference in height from the highest portion 11c of the convex portion 11a to the lowest portion 11e of the concave portion 11d is defined as a convex portion height H, and the half width (full width at half maximum) of the convex portion 11a of the concavo-convex structure is defined as W.

  The wire grid polarizer 10 according to the present embodiment is provided so as to be unevenly distributed on one side surface of the base material 11 having a concavo-convex structure extending in a specific direction on the surface and the convex portion 11a of the concavo-convex structure in a cross-sectional view. The pitch P1, which is the distance between two adjacent convex portions 11a, is 120 nm or less, and the height from the highest portion 11c of the convex portion 11a to the lowest portion 11e of the concave portion 11d. The height H, which is the difference, is configured to be 0.8 to 1.3 times the pitch P1. When the conductor 12 is provided so as to be unevenly distributed on the one side surface 11b of the convex portion 11a having the concavo-convex structure, the parallel transmittance can be improved by providing the conductor 12 so as not to be unevenly distributed on the other side surface of the same convex portion 11a. ,preferable.

  Since the conductor 12 of the wire grid polarizing plate 10 of the present invention is provided so as to be unevenly distributed on the one side surface 11b of the convex portion 11a which is a non-opposing surface of the two adjacent convex portions 11a in a cross-sectional view, the conductor 12 of the convex portion 11a. The pitch P1 and the pitch P2 of the conductor 12 are arranged at substantially the same interval. The conductors 12 arranged with a minute pitch P2 on the order of nanometers exhibit better polarization characteristics in a wider wavelength region as the pitch P2 becomes smaller. In the wire grid polarizing plate 10 according to the present embodiment, since the conductor 12 is in contact with air (refractive index 1.0), the pitch P2 of the conductor 12 is set to 1/4 to 1/1 of incident light (visible light). By setting it to 3, it becomes possible to show practically sufficient polarization characteristics. However, considering the optical symmetry, the pitch P1 is preferably 120 nm or less, and more preferably 100 nm or less. On the other hand, from the viewpoint of the shape of the conductor 12, the pitch P1 is preferably 80 nm or more. By carrying out like this, it is easy to achieve that the conductor 12 is provided so as to extend from the substantially lowest part of the concavo-convex structure to the highest part, and further exists above the top of the convex part 11a of the base material 11. Become.

  Further, in the sectional view, by setting the convex portion height H to 0.8 to 1.3 times the pitch P1, the conductor 12 extends in the vertical direction (the convex portion direction) and has a sufficiently high extinction ratio. This is preferable because the wire grid polarizing plate 10 having the conductor 12 having a height that provides the above can be easily manufactured. When the conductor 12 is formed by using the oblique vapor deposition method, depending on the shielding effect of the convex portion 11a, the growth direction of the conductor 12 becomes an oblique direction in a cross-sectional view, and the conductor 12 is connected to another adjacent conductor 12. There is. The connection between the conductors 12 at the time of forming the conductors 12 causes a decrease in parallel transmittance. In particular, when the pitch P1 is set to 120 nm or less, the narrowing of the pitch between the two adjacent protrusions 11a causes the formation of the conductors 12. In order to facilitate the connection of the conductors 12 at the time, it is important to control the shielding effect of the convex portions 11a.

  Here, by setting the height H of the convex portion to 1.3 times or less of the pitch P1, the shielding effect when forming the conductor 12 by the oblique deposition method can be made moderate, and the conductor 12 can be arranged in the vertical direction. Can grow into. Thereby, since the conductor 12 becomes a shape extended in the perpendicular direction in the cross-sectional view, it is possible to prevent the low transmittance due to the connection of the adjacent conductors 12. Moreover, since the area of the convex part 11a which occupies between the adjacent conductors 12 becomes sufficiently small, the shape of the conductor 12 in a cross-sectional view is substantially bilaterally symmetric, and the optical symmetry is increased. In addition, the reduction in the area of the convex portion 11a occupying the adjacent conductors 12 due to the convex portion height H being 1.3 times or less of the pitch P1 contributes to the improvement of the extinction ratio of the reflected light. There is an effect such as.

  However, when the height H of the convex portion is excessively reduced, the rate at which the height of the conductor 12 is increased with respect to the deposition amount is reduced. Although the height of the conductor 12 affects the extinction ratio of the reflected light, in order to efficiently produce the wire grid polarizer 10 having a sufficiently high height of the conductor 12, the height H of the protrusion is set to a pitch P1. It is preferably 0.8 times or more. That is, the wire grid polarizer 10 having high optical symmetry and high extinction ratio of transmitted light can be manufactured by setting the height H of the convex portion from 0.8 times to 1.3 times the pitch P1 in a sectional view. .

  Further, in a cross-sectional view, a position of approximately 9 / 10H of the convex height H that is a difference in height from the highest portion of the convex portion 11a to the lowest portion of the concave portion 11d is defined as a first height position (T1). When the position of approximately 1 / 10H is the second height position (T2), the width of the convex portion 11a at the first height position (T1) is set to the convex portion at the second height position (T2). The width is preferably 0.5 times or more and 1.0 times or less the width of 11a. The height position is based on the bottom of the recess 11d. Moreover, it is preferable that the value of the half width of the convex portion 11a of the concavo-convex structure is 0.05 times to 0.5 times the pitch P1.

  The width of the convex portion 11a at the first height position (T1) is 0.5 to 1.0 times the width of the convex portion 11a at the second height position (T2). By setting the value width to 0.05 to 0.5 times the pitch P1, the convex portion 11a extends in the substantially vertical direction from the bottom to the top and is sufficiently thinner than the pitch P1. Thereby, since the convex part area which occupies between the adjacent conductors 12 can be effectively reduced in a cross-sectional view, the wire grid polarizing plate 10 having high optical symmetry can be obtained.

  Moreover, it is preferable that the conductor 12 is extended from the substantially lowest part 11e of the concavo-convex structure to the highest part 11c, and at least a part thereof is provided above the highest part 11c of the convex part 11a of the concavo-convex structure. Thereby, the height of the conductor 12 can be increased, and the sectional area of the conductor 12 in a sectional view can be increased. That is, as the cross-sectional area of the conductor 12 increases in cross-sectional view, the area of the convex portion 11a occupying between the adjacent conductors 12 becomes relatively small, which not only contributes to an improvement in optical symmetry but also reflects light. It can be set as the wire grid polarizing plate 10 with a high extinction ratio of light. In addition, since the contact area between the convex portion 11a and the conductor 12 can be increased, the detachment / separation of the conductor 12 can be reduced, that is, the loss of the conductor 12 due to an external force or the like can be reduced.

  Moreover, it is preferable that the cross-sectional shape of the convex part 11a of a concavo-convex structure is a substantially rectangular shape in cross-sectional view. Thereby, the area of the convex part 11a which occupies between the adjacent conductors 12 can be made small.

  Further, in a cross-sectional view, the height from the highest portion 11c of the convex portion 11a to the highest portion of the conductor 12 is preferably 50 nm or more. Thereby, the extinction ratio of the transmitted light of the wire grid polarizer 10 can be increased.

  Further, in the cross-sectional view, it is preferable that the horizontal thickness of the conductor 12 between the first height position (T1) and the approximate highest portion 11c of the convex portion 11a is 20 nm or more. Thereby, the extinction ratio of the transmitted light and reflected light of the wire grid polarizer 10 can be increased.

  Moreover, it is preferable that the width | variety in the position (1st height position (T1)) of about 9 / 10H of the convex part 11a shall be 15 nm or more. In order to realize a high parallel transmittance and a high orthogonal reflectance suitable as a reflective polarizer, it is preferable to increase the thickness in the horizontal direction of the substantially highest portion 11c of the conductor 12. When the conductor 12 is formed by an oblique vapor deposition method having excellent mass productivity, the cross-sectional shape of the conductor 12 above the highest portion 11c of the convex portion 11a and the cross-sectional shape of the upper portion of the convex portion 11a are likely to be similar, It is preferable to increase the thickness in the horizontal direction of the upper portion of the convex portion 11a.

(Base material)
As the substrate 11, for example, an inorganic material such as glass or a resin material can be used. Among these, it is preferable to form the base material 11 using a resin material because there are merits such that a roll process is possible and the wire grid polarizing plate 10 can have flexibility (flexibility). Examples of the resin that can be used as the substrate 11 include polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, cycloolefin resin (COP), crosslinked polyethylene resin, polyvinyl chloride resin, polyacrylate resin, polyphenylene ether resin, Amorphous thermoplastic resins such as modified polyphenylene ether resin, polyetherimide resin, polyether sulfone resin, polysulfone resin, polyether ketone resin, polyethylene terephthalate (PET) resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin , Crystalline thermoplastic resins such as polybutylene terephthalate resin, aromatic polyester resin, polyacetal resin, polyamide resin, acrylic, epoxy, urethane, etc. Ultraviolet (UV) curable resins and thermosetting resins. Further, the base material 11 can be configured by combining a UV curable resin or a thermosetting resin with an inorganic substrate such as glass, the above-described thermoplastic resin, or triacetate resin, or by using them alone. Further, a thin film for improving the adhesion between the base material 11 and the conductor 12 may be provided on the surface of the base material 11.

  The concavo-convex structure on the surface of the substrate 11 is preferably rectangular when viewed in cross section. The rectangular shape includes repetition of the concave portion 11d and the convex portion 11a, and includes a trapezoidal shape, a rectangular shape, and a rectangular shape. In addition, before and after the inflection point when the contour of the concavo-convex structure in a cross-sectional view is regarded as a function, it is possible to have a curved portion where the curvature changes gently like a parabola, and the convex portion 11a has a constricted shape. Can be included. Due to the shape of the concavo-convex structure, it becomes easy to form the continuous conductor 12 by the oblique deposition method on the side surface 11b of the concavo-convex convex portion 11a on the surface of the substrate 11 and the bottom of the concave portion 11d.

  Moreover, the base material 11 should just be substantially transparent in the target wavelength range. It should be noted that extending in a predetermined direction is sufficient if the concavo-convex structure extends substantially in the predetermined direction, and each of the concave portion 11d and the convex portion 11a of the concavo-convex structure extends strictly in parallel. There is no need. Further, the pitch P1 of the concavo-convex structure is preferably 120 nm or less, and preferably at regular intervals. Note that “equal intervals” may be substantially equal intervals, and variations up to about ± 10% are acceptable. Just as the variation in the pitch P1 of the concavo-convex structure is allowed in a certain range, the height H of the convex portion and the width of the convex portion 11a in the cross-sectional view are also allowed in a certain range (for example, up to ± 10% variation). Is done.

  The manufacturing method of the base material 11 which has an uneven structure on the surface is not specifically limited. For example, the manufacturing method described in Japanese Patent No. 4147247 filed by the present applicant can be given. According to Japanese Patent No. 4147247, by using a metal stamper having a concavo-convex structure produced by an interference exposure method, the concavo-convex structure is thermally transferred to a thermoplastic resin, and the concavo-convex structure of the thermoplastic resin provided with the concavo-convex structure is extended. Free end uniaxial stretching is performed in a direction parallel to the existing direction. As a result, the pitch of the concavo-convex structure transferred to the thermoplastic resin is reduced, and a resin plate (stretched) having a fine concavo-convex structure is obtained. From the resin plate (stretched), a metal stamper having a fine concavo-convex structure can be produced using an electrolytic plating method or the like. By transferring and forming a fine concavo-convex structure on the surface of the base material 11 with this metal stamper, the base material 11 having the concavo-convex structure can be obtained.

  In addition, as a method of manufacturing the base material 11 using a metal stamper, there is a method of using a silicon-based substrate or the like in which a fine concavo-convex structure is manufactured by application of photolithography technology for semiconductor manufacturing. Using a silicon-based substrate having a fine concavo-convex structure as a mold, a resin plate having a fine concavo-convex structure on the surface is prepared. Subsequently, it is also possible to produce a metal stamper having a fine concavo-convex structure from the obtained resin plate having the fine concavo-convex structure on the surface using an electrolytic plating method or the like.

  Here, unevenness may be observed when visible light is irradiated onto a silicon-based substrate or the like in which a fine concavo-convex structure is produced by application of photolithography technology for semiconductor manufacturing. As one of the methods for producing the concavo-convex structure on the surface of the silicon-based substrate, a method of sequentially transferring (exposure) so that the pattern of the reticle is adjacent without leaving a gap can be given. The unevenness of the surface of the silicon-based substrate (hereinafter, also referred to as exposure unevenness) may be observed around the boundary (joint) of adjacent exposure regions, and this is because the uneven structure is aligned in a specific direction. In addition, it is particularly likely to occur when producing a concavo-convex structure in which the interval between adjacent convex portions 11a is 150 nm or less. In order to eliminate this uneven exposure, it is important to control the exposure position with high accuracy.For example, a silicon substrate or a concavo-convex structure of the silicon substrate is transferred to a surface having a concavo-convex structure. For example, it can be reduced or eliminated by performing a surface treatment such as reactive ion etching.

  The metal stamper described above is not limited as long as a fine concavo-convex structure can be transferred and formed on the surface of the substrate 11, and can have a flat plate shape, a cylindrical shape, or other shapes. In consideration of mass productivity, a cylindrical shape is preferable, and this enables a roll process in which a cylindrical metal stamper is provided in a plate cylinder as a plate material to continuously form an uneven shape.

  As a method for producing the cylindrical metal stamper, for example, a method of rounding a flat metal stamper into a cylindrical shape and joining the end portions can be cited. Here, when the surface of the bonding portion is rough, the portion of the substrate surface on which the uneven shape has been formed by the roll process becomes a rough surface, and the substrate on which the uneven shape is formed is formed. Although the material is wound into a roll shape, the substrate on the inner side and the outer side where the rough surface portion overlaps is locally strongly pressed. In addition, the surface of a junction part here means that there exists a wave | undulation, an unevenness | corrugation, and / or a level | step difference, and when visually observed (because the surface is rough), reflection is not uniform (it is not a mirror surface). Means.

  The concavo-convex structure of the wire grid polarizing plate according to the present invention is very fine with a pitch P1 of 120 nm or less, and therefore the concavo-convex structure is deformed when the substrate on which the rough surface portion overlaps is strongly pressed locally. , May become defective. In order to prevent such drawbacks, adjustment of the winding pressure of the roll, use of a slip sheet or an interlayer material, adjustment of the hardness of the base material, etc. can be mentioned, but in particular, the joint portion of the cylindrical metal stamper It is preferable to polish the surface. By smoothing the surface of the joint so as to be a mirror surface, deformation of the concavo-convex structure can be prevented, and the adhesion between the base material and the metal stamper at the time of forming the concavo-convex structure is improved, so that the occurrence of defects can be reduced.

(conductor)
The conductor 12 is provided on the concavo-convex structure surface of the substrate 11. As described above, the conductor 12 is preferably provided so as to be in contact with the one side surface 11b of the convex portion 11a and extend from the substantially lowest portion 11e to the highest portion 11c of the concavo-convex structure, and at least a part of the conductor 12 is provided. It is preferable to provide the projections 11a above the concavo-convex structure above the highest portion 11c.

  The conductor 12 is formed in a straight line with a predetermined pitch P2 substantially in parallel with the projections 11a of the concavo-convex structure on the surface of the base material 11 extending in a predetermined direction. The period of the linear conductor 12 is Is smaller than the wavelength of visible light, the polarized light component that reflects in the parallel direction with respect to the conductor 12 is reflected, and the polarized light component that is amplified in the vertical direction is transmitted through the polarized light separating member. As the conductor 12, aluminum, silver, copper, platinum, gold, or an alloy containing these metals as main components can be used, and the conductor 12 can be formed by an oblique sputtering method or an oblique evaporation method. In particular, it is preferable to form the conductor 12 using aluminum or silver because the absorption loss of visible light can be reduced.

<Conductor formation method>
As a method for forming the conductor 12, it is preferable to use an oblique deposition method in which deposition is performed from a direction inclined with respect to the vertical direction of the surface of the substrate 11 having a concavo-convex structure in consideration of productivity and optical characteristics. . The oblique vapor deposition method is a method in which, in a cross-sectional view of the substrate 11, a vapor deposition source deposits and laminates a metal while having a predetermined incident angle with respect to a direction perpendicular to the surface of the substrate 11. The preferable range of the incident angle is determined from the cross-sectional shape of the convex portion 11a having the concavo-convex structure and the conductor 12 to be manufactured, and is generally preferably 5 ° to 45 °, more preferably 5 ° to 35 °. Furthermore, it is preferable to control the cross-sectional shape such as the height of the conductor 12 by gradually decreasing or increasing the incident angle while considering the projection effect of the metal laminated during the vapor deposition. In addition, when the surface of the base material 11 is curving, it is good also as performing vapor deposition from the direction inclined with respect to the normal line direction of the surface of the base material 11. FIG.

  Specifically, it is 5 degrees or more and less than 45 degrees with respect to the vertical direction at the center of the deposition area on the surface of the base material 11 having a concavo-convex structure extending substantially in parallel with a predetermined pitch P1 in a specific direction. In this direction, the center of the vapor deposition source is provided, and the conductor 12 is formed on the concavo-convex structure. More preferably, the center of the evaporation source is provided in an angular direction that is 5 degrees or more and less than 35 degrees with respect to the vertical direction at the center of the deposition area on the surface of the substrate 11. Thereby, the conductor 12 can be selectively provided on any one side surface 11 b of the convex portion 11 a of the concavo-convex structure on the surface of the base material 11. In the case of vapor deposition while transporting the substrate 11, vapor deposition may be performed so that the center of the deposition area and the center of the vapor deposition source at a certain moment satisfy the above-described conditions.

  When the above-described oblique vapor deposition method is used, the extending direction of the convex portion 11a of the concavo-convex structure and the conductor 12 becomes equal. The amount of metal vapor deposition for achieving the shape of the conductor 12 of the wire grid polarizer in the present embodiment is determined by the shape of the convex portion 11a of the concavo-convex structure, but generally the average vapor deposition thickness is about 50 nm to 200 nm. . The average thickness here refers to the thickness of the deposited material on the assumption that the material is deposited on the smooth glass substrate from the direction perpendicular to the glass surface, and is used as a measure of the metal deposition amount.

  Further, from the viewpoint of optical characteristics, it is preferable to remove the unnecessary conductor 12 by etching. The etching method is not particularly limited as long as it does not adversely affect the base material 11 and a dielectric layer described later and can selectively remove the conductor 12 portion. From the viewpoint of productivity and the viewpoint of controlling the shape of the conductor 12, isotropic etching is preferable, and for example, an etching method of immersing in an alkaline aqueous solution is preferable. Further, when isotropic etching is used, it is possible to reduce or eliminate the apparent defects caused by the uneven exposure of the wire grid polarizer manufactured from the silicon-based substrate having the uneven exposure. Since the pitch P2 of the wire grid polarizer 10 in the present embodiment is small, when using a silicon substrate, the above-described problem of exposure unevenness is likely to occur, and therefore the defects caused by exposure unevenness can be reduced or eliminated. The use of isotropic etching is very suitable.

(Dielectric)
In the wire grid polarizer 10 shown in the present embodiment, in order to improve the adhesion between the material constituting the substrate 11 and the conductor 12, a dielectric comprising a dielectric material having high adhesion between the two is provided. A body layer can be used suitably. For example, silicon dioxide (Si) oxides, nitrides, halides, carbides or their composites (dielectrics in which other elements, simple substances, or compounds are mixed in a simple substance), aluminum (Al ), Chromium (Cr), yttrium (Y), zirconia (Zr), tantalum (Ta), titanium (Ti), barium (Ba), indium (In), tin (Sn), zinc (Zn), magnesium (Mg) ), Calcium (Ca), cerium (Ce), copper (Cu) and other metal oxides, nitrides, halides, carbides alone or a composite thereof. The dielectric material may be any material that is substantially transparent in the wavelength region where transmission polarization performance is desired. There are no particular limitations on the method of laminating the dielectric material, and physical vapor deposition methods such as vacuum vapor deposition, sputtering, and ion plating can be suitably used.

(Support substrate)
A support substrate can be used as the substrate 11 having the concavo-convex structure. As the support substrate, an inorganic material such as glass or a resin material can be used, but a wire grid polarizing plate can be manufactured by a roll process, and a flat resin material that can be easily bonded to other optical members is used. It is preferable. Moreover, there is no restriction | limiting in particular as a method of hold | maintaining the base material 11 with a support substrate, For example, use of an adhesive substance, the melt | fusion by heating, etc. can be mentioned.

  Examples of the resin material include polymethyl methacrylate resin (PMMA), polycarbonate resin, polystyrene resin, cycloolefin resin (COP), cross-linked polyethylene resin, polyvinyl chloride resin, polyacrylate resin, polyphenylene ether resin, and modified polyphenylene ether resin. , Polyetherimide resin, polyether sulfone resin, polysulfone resin, polyether ketone resin, polyethylene terephthalate resin (PET), polyethylene naphthalate resin, polyethylene resin, polypropylene resin, polybutylene terephthalate resin, aromatic polyester resin, polyacetal resin , Polyamide resin, triacetyl cellulose resin (TAC), etc., and ultraviolet (UV) curable resin such as acrylic, epoxy, urethane Thermosetting resins. Further, a UV curable resin or a thermosetting resin and an inorganic substrate such as glass, a thermoplastic resin, or the like may be combined or used alone.

  The in-plane retardation of the support substrate is preferably a low in-plane retardation value at a predetermined wavelength in order to avoid a decrease in the degree of polarization. For example, if use of visible light is considered, the retardation value at a wavelength of 550 nm Is preferably 30 nm or less. More preferably, it is 15 nm or less. Further, in order to prevent the occurrence of in-plane unevenness in the degree of polarization of the polarized light provided by the wire grid polarizer 10, it is necessary to manage the phase difference values at two arbitrary points on the surface of the support substrate. For example, use of visible light is considered. In this case, the in-plane retardation value difference at a wavelength of 550 nm is preferably 10 nm or less, and more preferably 5 nm or less. Examples of the supporting substrate having such characteristics include triacetyl cellulose resin (TAC), cycloolefin polymer resin (COP), polycarbonate resin (PC), polymethyl methacrylate resin (PMMA), and the like. It is preferable to use it.

(Protective film)
The surface of the wire grid polarizing plate 10 of the present embodiment having the conductor 12 can be bonded with a protective film that prevents the conductor 12 from being damaged due to an external force during conveyance. A protective film is comprised from the adhesion layer and base base material which show adhesiveness. There is no restriction | limiting in an adhesion layer, For example, adhesives, such as an acryl type, a silicone type, and a urethane type, can be used. The base substrate is not limited, and for example, a PET film can be used. Preferably, both the adhesive layer and the base substrate are preferably optically transparent. Optically transparent means that the transmittance is high at least in the visible light wavelength range, and this makes it easy to observe the state of the bonded wire grid polarizer 10.

  Here, by reducing the thickness of the adhesive layer of the protective film, it is possible to prevent the polarization separation characteristics from being lowered, such as a reduction in parallel transmittance and an increase in orthogonal transmittance of the wire grid polarizer 10. When the thickness of the adhesive layer of the protective film is reduced, the elasticity of the adhesive layer becomes relatively small, and the adhesion to the conductor deteriorates. Therefore, the migration of the adhesive layer component to the conductor reduces the polarization separation characteristics. This is because it can be prevented. In addition, when the adhesive layer of the protective film is extremely thinned, the adhesion force between the conductor 12 of the wire grid polarizer 10 and the adhesive layer is excessively reduced. Therefore, the thickness of the adhesive layer is 2 μm or more and 10 μm. The following is preferable.

<Reflective LCD projector>
Next, a projection display apparatus according to an embodiment of the present invention will be described. As a projector that is a projection-type image display device according to the present embodiment, there is a reflection-type liquid crystal projector using a reflection-type liquid crystal display element, and the polarization beam splitter of the reflection-type liquid crystal projector is related to the above-described embodiment. The wire grid polarizing plate 10 can be used suitably.

  With reference to FIG. 2, the projection type video display apparatus using the wire grid polarizing plate according to the above-described embodiment will be described. FIG. 2 is a conceptual diagram of a reflective liquid crystal projector which is an example of a projection display apparatus. As shown in FIG. 2, the reflective liquid crystal projector 20 according to the present embodiment includes a light source 21 such as an LED, a wire grid polarizing plate 10 as a polarization beam splitter, and a reflective liquid crystal that adds video information to the light source light. Display element 22. If necessary, a projection lens 23 for enlarging and projecting image light to which image information is added can be provided.

  The light source light emitted from the light source 21 enters the wire grid polarizer 10 which is a polarization beam splitter. There is no restriction | limiting in particular in a light source seed | species, For example, a laser etc. other than LED, a high pressure mercury lamp, etc. can be used suitably. Polarized light that has been polarized and separated by the wire grid polarizer 10 enters the reflective liquid crystal display element 22 and is modulated. The outgoing light (image light) emitted from the reflective liquid crystal display element 22 passes through the wire grid polarizing plate 10 and is enlarged by the projection lens 23, and then projected onto the screen.

  Further, the wire grid polarizer 10 is preferably arranged so that the conductor structure surface on which the conductor is formed faces the reflective liquid crystal display element 22. This is because the surface opposite to the conductor structure surface of the wire grid polarizer 10 has a relatively low reflectivity, so that unnecessary reflected light can be reduced, that is, stray light can be reduced, and the quality of the projected image light can be reduced. It is because it becomes possible to improve.

  In recent years, reflection type liquid crystal projectors have been miniaturized, and the optical path length between the light source and the polarization beam splitter cannot be increased, and the light source light is often diffused and enters the polarization beam splitter. . As an optical system of a reflection type liquid crystal projector, a pre-polarizing plate may be arranged between a light source and a polarizing beam splitter, and although the transmission axis directions of the polarizing beam splitter and the pre-polarizing plate are arranged orthogonally, In the case of diffused light, depending on the incident direction and incident angle of the diffused light source light, the transmission axis direction apparently intersects at an obtuse angle instead of being orthogonal. Here, when the extinction ratio of the reflected light of the polarizing beam splitter is low, the image quality is lowered, but the wire grid polarizer of the present invention can be preferably used because the extinction ratio of the reflected light can be increased. The extinction ratio of reflected light expressed as a ratio of orthogonal reflectivity to parallel reflectivity is preferably 50 or more, more preferably 90 or more, and a wire grid polarizing plate having a high extinction ratio of reflected light. By using it as a polarizing beam splitter, it is possible to provide a reflective liquid crystal projector with high image quality.

  Note that the extinction ratio of transmitted light expressed as a ratio of parallel transmittance to orthogonal transmittance is preferably 3000 or more at a transmittance of 85% at a wavelength of 555 nm, more preferably 4000 from the viewpoint of light and dark expression of an image. That's it. Moreover, in the transmittance | permeability 88%, 800 or more are preferable, More preferably, it is 1000 or more.

  The wire grid polarizing plate 10 according to the present embodiment can be used by being bonded to a smooth glass flat plate or can be curved. For example, in the case of bonding to a smooth glass flat plate, the size of the glass flat plate is made larger than that of the wire grid polarizing plate 10 to be bonded, so that the flat glass flat plate without touching the end of the wire grid polarizing plate 10 is obtained. It becomes possible to handle the bonded body of the wire grid polarizing plate 10 bonded to the substrate. When used as a polarizing beam splitter, it is preferable to use a large Abbe number in consideration of the influence of the Abbe number, and it is preferable to use a thin one. In addition, it is also possible to add an AR (anti-reflection) process or a moth-eye structure to the surface opposite to the conductor structure surface.

  The wire grid polarizing plate 10 according to the present embodiment can be used without damaging the optical characteristics in the visible light, near infrared light, and infrared light regions, so that the image display application using the regions, It is preferably used in pick-up applications and sensor applications. However, the present embodiment is not limited to the above-described embodiment, and various modifications can be made. Further, the material, quantity, and the like in the present embodiment described above are examples, and can be changed as appropriate. In addition, the present invention can be appropriately modified and implemented without departing from the technical idea of the present invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. First, the measurement method of the measured value in an Example is demonstrated.

<Measurement of transmittance>
For measuring the transmittance, RETS-100 manufactured by Otsuka Electronics Co., Ltd. or VAP-7070 manufactured by JASCO Corporation was used. The RETS-100 includes a polarizer (hereinafter also referred to as a measurement polarizer) in the vicinity of a light source and an analyzer (hereinafter also referred to as a measurement analyzer) in the vicinity of a light receiver, and performs measurement for holding a measurement sample. The sample stage has a single axis rotation axis and can be moved according to the purpose of measurement. The VAP-7070 includes a measurement polarizer in the vicinity of the light source, and can perform spectroscopic measurement by allowing linearly polarized measurement light to enter the measurement sample.

<Measurement of transmittance and reflectance>
U-4100 manufactured by Hitachi High-Technology Corporation was used for the measurement of transmittance and reflectance. The U-4100 has a measurement polarizer in the vicinity of the light source, and the measurement sample stage holding the measurement sample and the light receiver have the same uniaxial operation rotation axis. It can move.

<Measurement of in-plane retardation value>
As an in-plane retardation value measuring device, an ellipsometer (KOBRA-WR, manufactured by Oji Scientific Instruments) using a parallel Nicol method was used. The phase difference value when the wavelength of the measurement light was 550 nm and the incident angle was 0 degree was defined as the in-plane retardation value.

<Measurement method of refractive index>
A refractive index measurement device (manufactured by Metricon Corporation, laser refractive index measurement model 2010) was used for the measurement of the refractive index. When measuring the curable resin, the refractive index was measured after the curing treatment. From the measurement results of the refractive indices at wavelengths of 532 nm, 633 nm, and 824 nm using a refractive index measuring device, a wavelength dispersion diagram of the refractive index was obtained using Cauchy's dispersion formula, and a refractive index at a wavelength of 589 nm was obtained.

(Method for producing wire grid polarizer)
Next, a method for manufacturing the wire grid polarizer used in this example will be described below.

(Mold making)
Silicon-based substrates 1 to 10 each having a concavo-convex structure extending in one direction and having a concavo-convex structure pitch P1 of 145 nm or 100 nm in cross-sectional view were produced by a photolithography technique. Among these, the pitch P1 of the silicon substrate 1 was 145 nm, the pitch P1 of the silicon substrates 2 to 5 was 100 nm, and the pitch P1 of the silicon substrates 6 to 10 was 120 nm. The height of the silicon substrate 1 from the highest part of the convex part of the concavo-convex structure to the lowest part of the concave part is about 145 nm, the silicon type substrate 2 is about 150 nm, the silicon type substrate 3 is about 110 nm, and the silicon type substrate 4 is The thickness was approximately 90 nm, the silicon substrate 5 was 125 nm, the silicon substrate 6 was 85 nm, the silicon substrate 7 was 110 nm, the silicon substrate 8 was 120 nm, the silicon substrate 9 was 150 nm, and the silicon substrate 10 was 170 nm.

About 3 μm of acrylic UV curable resin (refractive index 1.52) is applied on a PET film (A-4300, manufactured by Toyobo Co., Ltd.) so that the concavo-convex structure surface of each silicon substrate is in contact with the UV curable resin. , Each superimposed. Using a UV lamp having a center wavelength of 365 nm, UV irradiation of 1000 mJ / cm ² was performed from the PET film side, and the uneven structure of the silicon-based substrate was transferred onto the PET film. When the surface of the PET film and the concavo-convex structure in cross-sectional view were observed with an SEM, it was confirmed that the concavo-convex structure extended in one direction and the concavo-convex structure of the silicon-based substrate was transferred. That is, the pitch of the transferred concavo-convex structure was the same as the pitch P1. As a conductive treatment, the uneven structure surface of the PET film described above was coated with platinum palladium by sputtering and then electroplated with nickel to prepare a nickel stamper having the uneven structure on the surface. It should be noted that a nickel stamper produced from a silicon substrate 1 having a pitch P1 of 145 nm is a mold A, and a nickel stamper produced from silicon substrates 2 to 5 having a pitch P1 of 100 nm is a mold B, D, E, and F. Nickel stampers manufactured from silicon-based substrates 6 to 10 having a pitch P1 of 120 nm are referred to as molds G to K, respectively.

Using the produced mold B, a concavo-convex structure was transferred to the surface of a 0.5 mm thick cycloolefin resin (hereinafter abbreviated as COP) plate by a hot press method, and a COP plate B having a concavo-convex structure on the surface was obtained. Produced. Subsequently, the COP plate B to which the concavo-convex structure on the surface of the mold B was transferred was subjected to surface treatment with UV-ozone on the concavo-convex structure surface. Using an ultraviolet surface treatment device (Photo Surface Processor, model: PM906N-2, manufactured by Sen Special Light Company), UV with an illuminance of 34 mW / cm ² at a wavelength of 254 nm is applied to the concavo-convex structure surface, and the concavo-convex structure of the COP plate B is applied. The surface to be irradiated was irradiated for 30 seconds. After the surface treatment, the COP plate B was covered with platinum palladium by sputtering as a conductive treatment, and then electroplated with nickel to produce a nickel stamper. A nickel stamper produced from the COP plate B after the surface treatment is used as a mold C.

(Preparation of concavo-convex structure transfer film using UV curable resin)
A transfer film having a concavo-convex structure on the surface was prepared using the molds A to K described above. The base material was a TAC film (TD80UL-H, manufactured by Fuji Film) made of a triacetyl cellulose resin having a thickness of 80 μm, and the in-plane retardation value at a wavelength of 550 nm of the TAC film was 3.5 nm. About 3 μm of an acrylic UV curable resin (refractive index 1.52) was applied to the TAC film, and a mold was superimposed on the TAC film. A UV lamp having a center wavelength of 365 nm was operated, and UV irradiation of 1000 mJ / cm ² was performed from the TAC film side to transfer the uneven structure of the mold onto the UV curable resin. The transfer film was prepared by peeling the TAC film from the mold and transferring the concavo-convex structure onto the surface of the substrate made of UV curable resin. The above operations were performed for the molds A to K, and transfer films A to K shown in Table 1 below were produced. Table 1 shows the results of observing the surface of each transfer film and the concavo-convex structure in cross-sectional view with an SEM. “Pitch P1” in Table 1 is the interval (pitch) between two adjacent convex portions, and “convex height H” is the height from the highest portion of the convex portion of the concavo-convex structure to the lowest portion of the concave portion. It is a difference, and the “convex width ratio (I)” is a value calculated by the following relational expression (1).

Formula (1)
Convex part width ratio = Convex part width at first height position / Convex part width at second height position

  In the formula (1), the first height position is a height of the convex portion that is a difference in height from the highest portion of the convex portion to the lowest portion of the concave portion in a cross-sectional view perpendicular to the extending direction of the concavo-convex structure. The position of H is approximately 9 / 10H, and the second height position is approximately 1 / 10H.

(Formation of dielectric layer using sputtering method)
Next, silicon dioxide was formed as a dielectric layer on the surface of the base material having the concavo-convex structure of each transfer film A to K by sputtering. The sputtering apparatus conditions were an Ar gas pressure of 0.2 Pa, a sputtering power of 770 W / cm ² , a coating speed of 0.1 nm / s, and a film was formed such that the dielectric thickness on the transfer film was 3 nm in terms of a flat film.

(Conductor formation using oblique deposition)
Next, aluminum (Al) was formed into a film by vacuum deposition on the surface of the substrate having the uneven structure of K from each transfer film A. The deposition conditions for Al were normal temperature, a degree of vacuum of 2.0 × 10 ⁻³ Pa, and a deposition rate of 40 nm / s. In the cross-sectional view, in the transfer films A, B, C, D, and E, Al was vapor deposited so that the vapor deposition angle with respect to the vertical direction of the substrate was 18 degrees and the Al average thickness was 110 nm. The average Al thickness is a value obtained by inserting a glass substrate having a smooth surface into the vapor deposition apparatus together with the transfer films A to K, and measuring the Al thickness on the vapor-deposited smooth glass substrate. It refers to the thickness of the deposit when it is assumed that the material is deposited from the vertical direction, and is used as a measure of the deposition amount.

(Examples 1 to 6 and Comparative Examples 1 to 5)
(Removal of unnecessary Al)
In order to remove unnecessary Al, transfer films A to K on which Al is vapor-deposited are immersed in a 0.1 wt% sodium hydroxide aqueous solution at room temperature, and then washed immediately with water to dry the film. Wire grid polarizers A1 to K1 of about 86% were prepared.

  When the concavo-convex structure and the shape of the conductor in the cross-sectional view of each of the wire grid polarizers A1 to K1 were observed with an SEM, the conductor was unevenly distributed on one side surface of the convex portion of the concavo-convex structure on the substrate (see FIG. 3). Moreover, the conductor extended from the substantially lowest part of the concavo-convex structure to the highest part, and at least a part thereof was provided above the highest part of the convex part of the concavo-convex structure. The height from the highest part of the convex part to the highest part of the conductor was 50 nm or more.

  Table 2 shows the “convex thickness (II)”, “convex shape”, “conductor thickness (III)” and “conductor height (IV)” of the wire grid polarizers A1 to K1. The “convex thickness (II)” is the width of the convex portion at the first height position, and the “convex shape” means the shape of the concavo-convex structure in a sectional view. Further, the “conductor thickness (III)” is a thickness at a portion where the horizontal thickness of the conductor is the thinnest part between the first height position and the approximately highest portion of the convex portion. "IV)" means the height from the lowest part to the highest part of the conductor.

The parallel transmittance of the wire grid polarizers A1 to K1 at the time of inclined incident light was measured with RETS-100 manufactured by Otsuka Electronics Co., Ltd. The parallel transmittance was measured under the condition that the rotation axis of the measurement sample stage and the transmission axis directions of the measurement polarizer, the measurement analyzer, and each wire grid polarizing plate to be measured were orthogonal to each other. . The incident angle of the measurement light incident on each wire grid polarizer A1 to K1 was set to -45 degrees and +45 degrees with the vertical direction of the wire grid polarizer being 0 degrees. The measurement wavelength was 555 nm, which is the wavelength at which human eyes feel light strongly. The absolute value of ΔTp _{(λ = 550 nm)} , which is the difference between the parallel transmittances Tp _{(λ = 555 nm)} at the incident angles of −45 degrees and +45 degrees, was calculated from the obtained parallel transmittance measurement results. Table 3 shows the calculated optical symmetry | ΔTp _{(λ = 555 nm)} |. When the optical symmetry | ΔTp _{(λ = 555 nm)} | is small, high optical symmetry is obtained.

  As shown in Table 3, Comparative Examples 1, 2, 3 and 5 have a large difference in parallel transmittance at incident angles of −45 degrees and 45 degrees and low optical symmetry compared to Examples 1 to 6. It was. The largest difference between Comparative Example 1 and Examples 1, 2, and 4 is the pitch P1, and the optical symmetry was improved by reducing the pitch P1. Moreover, the convex part height H of Comparative Examples 2, 3, and 5 is larger than 1.3 times the pitch P1, and the convex part width ratio (I) of Comparative Example 3 is smaller than 0.5 times. Therefore, the convex area occupied between adjacent conductors in a cross-sectional view is increased, and the optical symmetry is lowered. Examples 1 to 6, which are 1.3 times or less of the pitch P1, have high optical symmetry and can be suitably used.

(Examples 7 to 9 and Comparative Examples 6 to 9)
(Removal of unnecessary Al)
Each wire grid polarization in which a plurality of transfer films A, B, C, D, E, G and H prepared by depositing Al were prepared, and the immersion time in a 0.1 wt% sodium hydroxide aqueous solution (at room temperature) was changed. A plate was made. The operation of removing unnecessary Al was the same except for the immersion time, and was immediately washed after being immersed in an aqueous sodium hydroxide solution and dried. Of the obtained wire grid polarizers, the wire grid polarizers obtained from the transfer films A, B, C, D, E, G, and H are referred to as wire grid polarizers A2, B2, C2, D2, and E2. , G2 and H2.

  Next, the parallel transmittance and the orthogonal transmittance when the measurement light is incident from the vertical direction of the obtained wire grid polarizers A2, B2, C2, D2, E2, G2, and H2 are manufactured by JASCO Corporation. It was measured by VAP-7070. The measurement wavelength is a wavelength at which human eyes feel light strongly, 555 nm, and the measurement results of the obtained parallel transmittance and orthogonal transmittance are shown in the graph of FIG. The wire grid polarizing plate A2 is Comparative Example 6, the wire grid polarizing plate B2 is Comparative Example 7, the wire grid polarizing plate C2 is Comparative Example 8, the wire grid polarizing plate D2 is Example 7, and the wire grid polarizing plate E2 is an Example. 8. Wire grid polarizing plate G2 is Comparative Example 9, and wire grid polarizing plate H2 is Example 9.

  As shown in FIG. 4, since the wire grid polarizer A2 (Comparative Example 6) has a large pitch P1, the orthogonal transmittance is high, and the transmitted light has a low extinction ratio. The wire grid polarizer B2 (Comparative Example 7), C2 (Comparative Example 8), D2 (Example 7) and E2 (Example 8) have a pitch P1 as small as 100 nm, but the wire grid polarizer B2 (Comparative Example 7). Became a high orthogonal transmittance. This is because the height H of the convex portion with respect to the pitch P1 is high, so that the conductor thickness (III) of the conductor formed by the oblique deposition method is thinner than 20 nm. As one of the methods for increasing the conductor thickness (III) without changing the pitch P1 and the convex height H, the convex shape is a sine wave shape, and the horizontal thickness of the approximate highest portion of the convex portion is set. It is possible to reduce the thickness (wire grid polarizing plate C2, comparative example 8), but the optical symmetry is lowered. Therefore, it is preferable that the height H of the protrusion is 1.3 times or less of the pitch P1.

  In addition, compared with the wire grid polarizing plate D2 (Example 7), the wire grid polarizing plate E2 (Example 8) had a high orthogonal transmittance. This is because the height of the conductor formed by the oblique deposition method is low because the height H of the convex portion is small. This is the same for G2 (Comparative Example 9) with respect to the wire grid polarizing plate H2 (Example 9). However, when the height H of the convex portion is decreased, the optical symmetry is increased, but the high orthogonal transmittance is obtained. End up. Although it is a problem that can be solved by controlling the amount of vapor deposition at the time of vapor deposition, the increase in the amount of vapor deposition leads to a decrease in manufacturing efficiency, and in consideration of the fact that the cost increases, the height H of the convex portion is the pitch. This is preferably 0.8 times or more of P1.

(Extinction ratio of reflected light)
Orthogonal reflectance and parallel reflection when the measurement light is incident on the conductor structure surface of the wire grid polarizer C1 (Comparative Example 3), E1 (Example 2), and F1 (Example 3) with a pitch P1 of 100 nm. The rate was measured with a spectrophotometer (manufactured by Hitachi High-Technology Corporation, U-4100). The operation rotation axis of the measurement sample stage and the transmission axis direction of each wire grid polarizing plate to be measured are parallel, and the operation rotation axis of the measurement sample stage and the transmission axis direction of the polarizer near the light source of the measurement apparatus are orthogonal to each other. . The angle of the measurement light incident on each wire grid polarizing plate was set to 45 degrees with the vertical direction of the wire grid polarizing plate being 0 degrees, and the orthogonal reflectance and parallel reflectance at a wavelength of 555 nm at the light incident angle were measured. The results are shown in Table 4. After the measurement, the ratio of the orthogonal reflectance to the parallel reflectance (the extinction ratio of the reflected light) was calculated. As a result, the wire grid polarizer C1 was 19, the wire grid polarizer E1 was 101, and the wire grid polarizer F1 was 51. .

表４に示すように、ワイヤグリッド偏光板Ｅ１及びＦ１は、断面視において、凸部高さＨをピッチＰ１の１．３倍以下とすることにより、隣接する導電体間に占める凸部の面積が十分に小さくなるため、反射光の消光比が向上した。

As shown in Table 4, the wire grid polarizers E1 and F1 have a convex area occupied between adjacent conductors by making the convex part height H 1.3 times or less of the pitch P1 in a sectional view. Is sufficiently small, and the extinction ratio of reflected light is improved.

(Examples 10 to 12 and Comparative Example 10)
(Optical properties before and after protective film bonding)
Protective film 1 or protective film 2 having acrylic adhesive 1 (refractive index 1.47) on a PET film as a base substrate, and protection having PET adhesive 1 on a PET film as a base substrate The film 3 or the protective film 4 was bonded to the surface having the conductor of the wire grid polarizing plate E1, and the parallel transmittance and the orthogonal transmittance before and after the protective film bonding were measured. The protective film 1 and the protective film 2 differed only in the layer thickness of the acrylic adhesive 1, the layer thickness of the protective film 1 was 2.5 micrometers, and the protective film 2 was 10 micrometers. Moreover, the protective film 3 and the protective film 4 differed only in the layer thickness of the silicon adhesive 1, and the protective film 3 was 10 micrometers in thickness, and the protective film 4 was 20 micrometers. In addition, the optical measurement used JASCO Corporation VAP-7070.

  The case where the protective film 1 is used is Example 10, the case where the protective film 2 is used is Example 11, the case where the protective film 3 is used is Example 12, and the case where the protective film 4 is used is Comparative Example 10. did.

  Before the protective film was bonded, the parallel transmittance Tp1 and the orthogonal transmittance Tc1 at a wavelength of 555 nm of the wire grid polarizing plate E1 were measured. Then, after bonding the protective film and leaving still at room temperature for 30 minutes, the bonded protective film was peeled off and the parallel transmittance Tp2 and orthogonal transmittance Tc2 in wavelength 555nm of the wire grid polarizing plate E1 were measured. From Tp1, Tp2, Tc1 and Tc2, ΔTp and ΔTc were calculated using the following formula (2). In addition, it means that there is little optical characteristic fall of the wire grid polarizing plate by a protective film, so that (DELTA) Tp is small.

Formula (2)
ΔTp = | Tp1-Tp2 |
ΔTc = | Tc1-Tc2 |

  As shown in Table 5, the optical characteristics of Example 12 were less degraded than Comparative Example 10. By reducing the thickness of the adhesive layer, it was possible to prevent a decrease in polarization separation characteristics such as a change in parallel transmittance and orthogonal transmittance of the wire grid polarizing plate E1.

  When Example 10 and Example 11 are compared, in terms of optical characteristics, Example 9 in which the thickness of the adhesive layer is thin is preferable, but it is difficult to say that the adhesion of the wire grid polarizer E1 to the conductor is good. , The frequency of air bubble mixing during bonding increased. This is because the adhesion of the wire grid polarizer to the conductor has been excessively reduced. Therefore, the thickness of the adhesive layer is preferably 2 μm or more and 10 μm or less.

  In addition, this invention is not limited to the said embodiment, It can implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited thereto, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  According to the present invention, since the wire grid polarizer is excellent in optical symmetry, it can be used for realizing a high-quality liquid crystal display device.

DESCRIPTION OF SYMBOLS 10 Wire grid polarizing plate 11 Base material 11a Convex part 11b One side surface 11c Highest part 11d Concave part 11e Lowest part 12 Conductor H Convex part height

Claims (12)

A wire grid polarizing plate having a base material having a concavo-convex structure extending in a specific direction on the surface, and a conductor provided so as to be unevenly distributed on one side surface of the convex portion of the concavo-convex structure,
In the cross-sectional view in the vertical direction with respect to the extending direction of the convex-concave structure, the pitch P1 is an interval between adjacent two of the protrusions is at 120nm or less, and a high from the highest portion of the convex portion to the lowest portion of the recess The height H of the convex portion, which is the difference in thickness, is 0.8 to 1.3 times the pitch P1,
Wherein in the cross-sectional view in the vertical direction with respect to the extending direction of the concavo-convex structure, said difference in height is the position of 9 / 10H of the convex height H from the highest portion of the convex portion to the lowest portion of the concave first of when the height position state, and are horizontal thickness 20nm or more of the conductors between the said first height position to a maximum portion of the convex portion,
The conductor extends from the lowest part of the concavo-convex structure to the highest part, and at least a part of the conductor is provided above the highest part of the convex part of the concavo-convex structure,
The conductor has a thickness in a horizontal direction at a position of 1 / 10H of the height H of the convex portion is larger than a thickness in a horizontal direction at a position of 9 / 10H of the height H of the convex portion. The wire grid polarizing plate characterized in that the horizontal thickness at the highest portion is thinner than the horizontal thickness at the highest portion of the convex portion . In the cross-sectional view in the vertical direction with respect to the extending direction of the concave and convex structure, the position of the 9 / 10H of the convex height H is the height difference of at least part of the recess from the highest portion of the convex portion first The width of the convex portion at the first height position is the convex portion at the second height position when the height position is one and the position of 1 / 10H is the second height position. a is below 1.0 times 0.5 times the width, the value of the half width of the convex portion of the concavo-convex structure, and characterized by a 0.5-fold from 0.05 times the pitch P1 The wire grid polarizing plate according to claim 1. The wire grid polarization according to claim 1 or 2, wherein a cross-sectional shape of the convex portion of the concavo-convex structure is a substantially rectangular shape in a cross-sectional view perpendicular to the extending direction of the concavo-convex structure. Board. In the cross-sectional view in the vertical direction with respect to the extending direction of the convex-concave structure of claims 1 to 3, the height of the highest portion of the convex portion to the highest portion of the conductor, characterized in that at 50nm or more The wire grid polarizing plate in any one. In the cross-sectional view in the vertical direction with respect to the extending direction of the convex-concave structure, claim 1, the width in the first height position of 9 / 10H of the convex portions is equal to or is 15nm or more claims 4 The wire grid polarizing plate in any one. 6. The wire grid polarizer according to any one of claims 1 to 5 , wherein the conductor is etched by isotropic etching. The wire grid polarizer according to any one of claims 1 to 6 , wherein the concavo-convex structure is produced by transferring a silicon-based substrate having a concavo-convex structure on the surface as an original plate. . The wire grid polarizing plate according to any one of claims 1 to 7 , further comprising a protective film for protecting the conductor, wherein a thickness of the adhesive layer of the protective film is 2 µm or more and 10 µm or less. . In a cross-sectional view perpendicular to the extending direction of the concavo-convex structure, the parallel transmittance at a light incident angle of −45 degrees and +45 degrees when the vertical direction of the wire grid polarizing plate is 0 degree is ( The wire grid polarizing plate according to any one of claims 1 to 8 , wherein a difference in Tp) is 4% or less. 1 SL and mounting of the wire grid polarizer according to claim, a projection type image display apparatus having a light source and a reflective liquid crystal display device,
The light emitted from the light source is transmitted or reflected by the wire grid polarizer and enters the reflective liquid crystal display element, and the light modulated by the reflective liquid crystal display element is reflected by the wire grid polarizer or A projection-type image display device that projects an image through transmission. 11. The projection display apparatus according to claim 10 , wherein a conductor structure surface of the wire grid polarizing plate is disposed so as to face the reflective liquid crystal display element. A method of manufacturing a wire grid polarizer comprising: a step of forming a concavo-convex structure extending in a specific direction on a substrate surface; and a step of forming a conductor so as to be unevenly distributed on one side surface of the convex portion of the concavo-convex structure. There,
The step of forming the uneven structure is in the cross-sectional view in the vertical direction with respect to the extending direction of the convex-concave structure, the pitch P1 is an interval between adjacent two of the convex portion is formed in 120nm or less, the protrusions The convex part height H, which is the difference in height from the highest part to the lowest part of the concave part, is formed from 0.8 times to 1.3 times the pitch P1,
The step of forming the conductor, said in the cross-sectional view in the vertical direction with respect to the extending direction of the convex-concave structure, the convex height H from the highest part which is the difference in height to the lowest portion of the concave portion of the convex portion When the position of 9 / 10H is set to the first height position, the horizontal thickness of the conductor between the first height position and the highest portion of the convex portion is 20 nm or more. Forming the conductor , extending from a substantially lowest part of the concavo-convex structure to the highest part, and at least a part of the conductor is provided above the highest part of the convex part of the concavo-convex structure. A conductor is formed, and the thickness in the horizontal direction at a position of 1 / 10H of the height H of the protrusion is larger than the thickness in the horizontal direction at a position of 9 / 10H of the height H of the protrusion. The horizontal thickness at the highest part of the projection is horizontal at the highest part of the convex part. Method of manufacturing a wire grid polarizer, which comprises forming the conductor to be thinner than the thickness of the direction.

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